1 /* 2 * Copyright (C) 2016 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 #include <atomic> 17 #include <thread> 18 #include <functional> 19 #include <linux/videodev2.h> 20 21 22 typedef v4l2_buffer imageBuffer; 23 24 25 class VideoCapture { 26 public: 27 bool open(const char* deviceName); 28 void close(); 29 30 bool startStream(std::function<void(VideoCapture*, imageBuffer*, void*)> callback = nullptr); 31 void stopStream(); 32 33 // Valid only after open() 34 __u32 getWidth() { return mWidth; }; 35 __u32 getHeight() { return mHeight; }; 36 __u32 getStride() { return mStride; }; 37 __u32 getV4LFormat() { return mFormat; }; 38 39 // NULL until stream is started 40 void* getLatestData() { return mPixelBuffer; }; 41 42 bool isFrameReady() { return mFrameReady; }; 43 void markFrameConsumed() { returnFrame(); }; 44 45 bool isOpen() { return mDeviceFd >= 0; }; 46 47 private: 48 void collectFrames(); 49 void markFrameReady(); 50 bool returnFrame(); 51 52 int mDeviceFd = -1; 53 54 v4l2_buffer mBufferInfo = {}; 55 void* mPixelBuffer = nullptr; 56 57 __u32 mFormat = 0; 58 __u32 mWidth = 0; 59 __u32 mHeight = 0; 60 __u32 mStride = 0; 61 62 std::function<void(VideoCapture*, imageBuffer*, void*)> mCallback; 63 64 std::thread mCaptureThread; // The thread we'll use to dispatch frames 65 std::atomic<int> mRunMode; // Used to signal the frame loop (see RunModes below) 66 std::atomic<bool> mFrameReady; // Set when a frame has been delivered 67 68 // Careful changing these -- we're using bit-wise ops to manipulate these 69 enum RunModes { 70 STOPPED = 0, 71 RUN = 1, 72 STOPPING = 2, 73 }; 74 }; 75 76
